Week 2 + 3

Question 1

What do the commands below do?

tilda (~) command?

whoamii command?

pwd command?

cd command?

Answer 1

tilda(~) goes to the home directory

whoami checks who the user is

pwd checks the current working directory(where u are)

cd command changes directory listed after cd

Question 2

What are Paths?

Types of Paths?

Answer 2

List of directories separated by /.
example: /home/tenzing/desktop

Types: Absolute(starts with /), and Relative

Question 3

Differences with Absolute and Relative paths?

Answer 3

Absolute: starts with / root directory

Relative: starts at current directory. use .. to go back a directory or ../../

Question 4

What does ls -a command do?

what does ls -l command do?

Answer 4

Shows all hidden files and folders, hidden folders will have a . in front

Gives a long list with detailed info.

1st Column: File type and access
permissions
* 2nd Column: # of HardLinks to the
File
* 3rd Column: Owner and the
creator of the file
* 4th Column: Group of the owner

Question 5

In the ls -l command
The first character on each line indicates the type.
List the types:

Answer 5

d (directory)
- (regui]lar file)
l (symbolic link)
s (socket)
p (pipe)
b (block file)
c (character file)

Question 6

drwxr-xr-x

define this

Answer 6

d(type)
rwx(read-write-execute for owner)
xr(perms for group)
x(perms for others)

r = read
x = execute
w = write

Question 7

What does -h command do?

And describe human-readable format?

Answer 7

when file size too big makes it easier to read. M - megabytes, G - Gigabytes, T- Terabytes.

Question 8

What are different ways to sort with ls command?

Answer 8

ls -r (recursive, sort backwards)

ls -s (sort by file size)

ls -t (sort by time)

Question 9

How to use ls to get a detailed timestamp?

Answer 9

ls –full-time

Question 10

How to get to the manual page on how to use glob?

Answer 10

man 7 glob

Question 11

What does the asterisk(*) do? and uses?

Answer 11

• • represents any name
    d - name that ends with d
    a - name that starts with a
    c - name that contains c
    a*c - name that starts w/ a and ends w/ c

Question 12

What does the ? character do?

Answer 12

??? - names that contain 3 characters

d.??? - name that starts with d. then contains any 3 characters

Question 13

What does the square brackets do
[ ]?

Answer 13

[abc]d - begins with either a, b, or c and ends with d.

[a-zA-Z][0-9] - begins with any letter lower or uppercase and ends with any number from 0-9

Question 14

What does [!] do?

Answer 14

[!abc]d – this is a name that does NOT begin with either character ‘a’
or ‘b’ or ‘c’ and ends with character ‘d’

Question 15

What do the curly brackets do?

Answer 15

Curly brackets {} are used to specify terms that are separated by commas and each term must be a name or a wildcard.

Same as IN (value1, value2) in DBAS

Question 16

How to create text files?

Answer 16

touch newfile.txt

or

cat > newfile.txt
content
content
CTRL-D to save

Question 17

How to create directory?

and

How to create 3 directories at once? named ‘a’, ‘b’, ‘c’

Answer 17

mkdir directoryname

mkdir a b c

Question 18

Create a two parents(o and s)
and s has two children

Answer 18

mkdir -p o/p/q/r s/{sub1,sub2}

Question 19

How to remove directories and files?

Answer 19

rmdir to remove directory

rm filename or
rm -r filename to force delete

Question 20

How to copy and move files and directories?

Answer 20

copy files:
cp filename end location
copy directory:
cp -r directoryname endlocation

move files:
mv filename endlocation

Use -n for no clobber, to prevent cp and mv commands from overwriting content at the destination

Question 21

How to rename files or directories?

rename directory ‘a’ to ‘aaa’ and move ‘aaa’ to ‘b’

Answer 21

mv directory newname

mv a b/aaa

Question 22

Types of text editors?

Answer 22

nano and vim

Question 23

Explain the difference between single hypen(-l) and double hyphen?

Answer 23

Single hypen options are for short form (-h), while double hypen are for full words (–human-readable).

Question 24

How to check for history?

Answer 24

history command

Question 25

Create a variable called greet and assign it a value of Hello. Then Display it.

Answer 25

greet=Hello

echo $greet

Question 26

Export the variable greet as an environment variable. Then unset it.

Answer 26

export greet
env | grep greet

unset greet

Question 27

What are the 4 types of commands

Answer 27

Internal - part of the shell(cd)

External - require executable files to run (which command)
type -a echo

Aliases - short name given to long commands

Functions - Complex structures that can be used to create new commands or change behaviour of existing commands

Question 28

What is root user

Answer 28

Root is a superuser account.

Recommended that you use sudo instead as a home user.

Question 29

The CLI is a very powerful and fast interface that allows users ______ ________ _______ _________ ______ _______ _________.

Answer 29

The CLI is a very powerful and fast interface that allows users to complete various tasks
by issuing commands.

Question 30

Once a user has entered a command, the terminal then accepts what the
user has typed and passes it to _ ___.

Answer 30

Once a user has entered a command, the terminal then accepts what the
user has typed and passes it to a shell.

Question 31

A shell is an application that allows users to use the services of an operating
system

It is named a shell because it ___________________________________.

_____ is the most commonly used shell in Linux.

Answer 31

A shell is an application that allows users to use the services of an operating
system

It is named a shell because it is the outermost layer around the operating system.

Bash is the most commonly used shell in Linux.

Question 32

breakdown the components:
tenzing@comp:~$

Answer 32

tenzing@comp:~$

tenzing: Username
comp: System name
~: current directory(~ means home)

Question 33

Two types of variables in Bash shell?

Answer 33

Local variables - store values, perform calculations, etc.
Environment variables - used to control the Linux run time environment

Question 34

Format for making a local variable?

How to check the value of a variable named “sum”

Answer 34

$ var=Hello
var(variable name)=Hello(value)

echo $sum

Question 35

There are many environment variables. For example: _____, _____, and ________ variables.

Answer 35

There are many environment variables. For example: PATH, HOME, and HISTSIZE variables.

Question 36

The ___ command outputs a list of the environment variables.

The _______ command is used to turn a local variable into an environment variable.

Variables can be removed using the unset command: _____ ___

Answer 36

The env command outputs a list of the environment variables.

The export command is used to turn a local variable into an environment variable.

Variables can be removed using the unset command: unset var

Question 37

Internet commands are the shell built-in commands.

Two Internal commands are ____ and ______

Answer 37

Two Internal commands are cd and echo

you can use the type command to check.

Question 38

External commands can be executed by typing _____ ______ __________ _______ _____ ________ __________.

Answer 38

External commands can be executed by typing the complete path to the executable file for that command.

the type command displays the location of external commands.